Back in the '80s, the production "Dreamgirls" was taking Broadway by storm. It sold out theaters, produced chart-topping singles and earned 13 Tony Award nominations, winning six. At the center of the excitement was actress Sheryl Lee Ralph, whose character rose to fame as the lead singer of an African-American girl group in the 1960s -- a story rumored to be inspired by The Supremes and lead vocalist Diana Ross.

For three decades, those rumors have persisted, but Ralph tells "Oprah: Where Are They Now?" that from the very beginning, "Dreamgirls" writer Tom Eyen was simply intent on casting three African-American women as a singing trio.

"He cast specifically, but he was always very clear: He said, 'If you play Diana Ross, they will sue us,'" Ralph recalls.

Still, a Broadway urban legend swirled throughout the community that Ross snuck into the theater and watched "Dreamgirls" incognito. "There was a rumor that she would come in -- shrouded, dark glasses -- and sat in the back... and wasn't happy," Ralph says.

Ralph had never met Ross herself -- until a memorable lunch one winter at the famed restaurant Sardi's. Ralph was dining with her agent when the legendary singer walked in.

"Who breezes in like a warm breeze of summer in the middle of winter? Diana Ross," Ralph says.

Ralph quickly turned around and went back to her table, as her agent offered his sympathy over the icy encounter. But that wasn't the last time the women would meet. The next time, it turned out differently.

"Years later, I would see her again," Ralph says. "We talked about our children, we talked about life and that was that. I was very happy."